1. Field of the Invention
The present invention relates generally to methods, systems and apparatus for controlling trains traveling in a track network made up of multiple tracks with signals associated with portions of the track and, in particular, to a system and method of controlling a train by predictively enforcing signal aspects as the train is moving through the track network.
2. Description of Related Art
As is known in the art, train control systems are used for monitoring, tracking and operating trains traversing tracks throughout a track network. In order to make appropriate train control decisions regarding how the train should be operated, whether manually, automatically or semi-automatically, important information and data must be obtained. In addition, and in order to provide for safe traffic control and avoid accidents or collisions, signals are provided throughout the track network, and each signal is typically associated with a block or section of track. The aspects of these signals are normally generated by the wayside signals and communicated to the train, where some signal or other indication is provided to the train operator regarding upcoming track signal aspects and track status.
In one example of the prior art, certain wayside signals, e.g., permissive signals, are positioned along the track, and the portion of track may be in a territory where cab signals can be obtained or generated. These cab signals (or on-board signals) provide the current wayside signal indication, and often provided in a territory equipped for such operation where wayside signals are positioned along the track. Various mechanisms and communication systems may be provided or used to transmit the signal indication or aspect from the upcoming wayside signal to the train.
Normally, automatic cab signal systems are implemented in a territory equipped with track circuits for train detection, including logic controllers that can determine the proper signal indication to display and provide for communication between adjacent logic controllers via the track rails. In addition, the locomotives or trains are equipped to receive indications from the track rails, and indicator units displaying the signal indications to the train engineer or operator, such as via a visual display or the like. A permissive signal is a signal where the “stop” indication means “stop and proceed at restricted speed.” Usually identified by a number plate, some permissive signals also have a plate with a letter “G,” indicating that the train may pass a signal having this “stop” aspect without stopping, but at restricted speed. Further, this “stop” aspect or indication may also be an absolute signal that requires the operator stop the train and proceed only with authority from dispatch.
It should be noted that many, but not all, cab signal-equipped territories include wayside signal heads of the color-light variety. In such systems: (1) a “clear” signal displays green and indicates that it is safe to proceed; (2) an “advance approach” signal is flashing yellow and indicates that the train may proceed but should be prepared to stop at the second upcoming wayside signal; (3) an “approach” signal is solid yellow, and indicates that the train can proceed but should be prepared to stop before any part of the train or engine passes the next signal; and (4) a “stop and proceed” signal is red, and indicates that the train should stop before any part of the train or engine passes the signal, and should then proceed at restricted speed to the next signal.
These wayside signal indications or aspects have corresponding signal indications or aspects in the cab or in an on-board location. In particular, known cab signals include: (1) a “restricting” signal that is half red and half yellow and indicates that the train should proceed at restricted speed; (2) an “approach” signal that is solid yellow and indicates that the train can proceed, but should be prepared to stop before any part of the train or engine passes the next signal; (3) an “advance approach” signal that is half yellow and half green and indicates that the train can proceed, but should be prepared to stop at the second signal; and (4) a “clear” signal that is solid green and indicates that the train may proceed as normal.
In operation and under some conditions, a train may be following another train, and can encounter a sequence of signals indicating “approach,” “advance approach,” “approach,” etc., which tends to lulls the train operator into a lower state of vigilance. After encountering a number of these “approach”/“advance approach” cyclical indications, the train may next encounter a signal indicating “stop and proceed.” One typical reason for this “stop and proceed” signal is that another train is occupying the next, upcoming track circuit or block. This problem is further exacerbated in cab signal territory, where in certain scenarios the “approach” indications will upgrade to the less restrictive “advance approach” signal indication. When the operator is lulled into a lower state of vigilance, he or she may not be operating the train in an appropriate manner to comply with the next, upcoming wayside signal aspect, e.g., “stop and proceed.” Therefore, due to this diminished state of vigilance, accidents or collisions may occur between trains (or other similar noncompliance issues may arise with respect to the next, upcoming signal).
FIGS. 1 and 2 illustrate the operation of two trains TR1, TR2 proceeding along a track T in a track network TN, where multiple wayside signals S are positioned along the track T, and a cab signal S is provided to the operator in the train TR1, TR2. With reference to FIG. 1(a), the cab signal S in the train TR1 indicates “clear,” and this train TR1 is approaching a wayside signal S that also indicates “clear.” This wayside signal S is the source of information to the cab signal equipment of train TR1 and provides a “clear” indication. Train TR2 is stopped just after passing a wayside signal S, which now provides a signal indication or aspect of “stop and proceed” to trains following train TR2, e.g., train TR1. The cab signal equipment of train TR2 indicates “clear.”
In FIG. 1(b), train TR1 has passed the second wayside signal S, thus “knocking it down” to a “stop and proceed” indication for trains following train TR1. Further, train TR1 cab signal S indicates “clear,” and train TR1 is approaching a flashing yellow wayside signal S, indicating “advance approach.” This wayside signal S is the source of information to the train TR1 cab signal system. It should be recognized that “advance approach” means that the crew should be prepared to stop at the second wayside signal S in the forward direction, which is the wayside signal S that train TR2 has just passed.
In FIG. 1(c), train TR1 has passed the “advance approach” wayside signal S, knocking it down to “stop and proceed.” Also, train TR1 cab signal system indicates “advance approach.” Train TR1 is now approaching a wayside signal S indicating “approach,” which means that the crew must be prepared to stop before passing the next wayside signal S. In FIG. 1(d), train TR1 has passed the wayside signal S previously indicating “approach,” thus knocking it down, and is now approaching a wayside signal S indicating “stop and proceed.” Train TR1 cab signal system now displays “approach,” which again means that the crew must be prepared to stop the train before passing the next, upcoming wayside signal.
Finally, in FIG. 1(e), train TR1 has stopped before passing the next wayside signal S, which indicates “stop and proceed.” Therefore, no collision or other issue has arisen, since train TR2 has stopped on a specific portion or section of track, and the signal indication or aspect provided to train TR1 continually downgraded as train TR1 approached train TR2, culminating in the “stop and proceed” indication, which is easily complied with based upon the gradual and downgraded nature of the signal S indications.
In another example, and as illustrated in FIG. 2, train TR1 is following train TR2, and train TR2 is initially moving. As seen in FIG. 2(a), train TR1 cab signal system is indicating “advance approach,” and is nearing a wayside signal S indicating “approach,” which, as discussed, means train TR1 must be prepared to stop before passing the next wayside signal S (which, in this example, is indicating “stop and proceed”). Train TR2 is also moving, and its cab signal system is indicating “clear.”
In FIG. 2(b), train TR1 has passed a wayside signal S, knocking it down to “stop and proceed,” and train TR1 cab signal system now indicates “approach.” The next wayside signal is indicating “stop and proceed.” In FIG. 2(c), train TR2 has advanced far enough that the rearward wayside signal S has improved from “stop and proceed” to “approach.” This, in turn, upgrades the train TR1 cab signal indication to “advance approach.” In FIG. 2(d), train TR1 has passed the next wayside signal S, and train TR1 cab signal system now indicates “approach.” Train TR2 has stopped just past a wayside signal S.
This sequence of events may repeat a number of times, with train TR1 cab signal system alternatively indicating “advance approach,” “approach,” “advance approach,” “approach,” etc. Further, it is this sequence of events that may cause the operator of the train TR1 to become complacent. In particular, the crew expects train TR2 to continue moving, and therefore expects the signal indication in train TR1 cab signal system to continue cycling between “approach” to “advance approach.”
However, and as illustrated in FIG. 2(e), and due to the stoppage of train TR2, train TR1 is now approaching a wayside signal S indicating “stop and proceed,” which requires that the train TR1 stop before any part of the train TR1 or engine passes the signal S, and then to proceed at restricted speed to the next signal S. However, the crew or operator may not be prepared to stop the train TR1 before passing this next, upcoming wayside signal S, since they are expecting the train TR1 cab signal indication to upgrade to “advance approach.” Not being able to stop in time, train TR1 will collide with train TR2.
There are available different systems and methods for communicating with wayside equipment implementing safety features and controlling trains as they travel through the track network. For example, one or more of the following patents/publications describe train monitoring, control and/or safety systems or functions for use in operating a train in a train network: U.S. Pat. Nos. 7,236,860; 7,036,774; 6,996,461; 6,957,131; 6,903,658; 6,865,454; 6,863,246; 6,853,888; 6,845,953; 6,824,110; 6,609,049, all to Kane et al.; U.S. Pat. No. 6,688,561 to Mollet et al.; U.S. Pat. No. 5,452,870 to Heggestad; U.S. Pat. No. 6,112,142 to Shockley et al.; U.S. Pat. No. 4,196,412 to Sluis et al.; and Publication Nos.: 2006/0080009 to Kane et al.; 2006/0015224 to Hilleary; 2005/0110628 to Kemwein et al.; 2004/0182970 to Mollet et al.; and WO 2005/066731 to Kane et al.
These prior art systems and methods exhibit various drawbacks and deficiencies. Further, many of these prior art systems are amenable to further augmentation or beneficial, functional enhancements in order to provide increased vigilance and maintenance of safe conditions at various portions along the track in the track network. In addition, there remains a need in the art for increasing operator vigilance, thus enhancing the safety of trains traveling within the track network and for providing protection of the operators, crew, pedestrians, motorists, etc.